.flex-grow{
    display:flex;
    align-items: stretch;
}

.flex-grow item{
    border: 1px solid;
}
.flex-grow div:nth-child(1){
    flex-grow: 1;
}


.flex-grow div:nth-child(2){
    flex-grow: 1;
}

.flex-grow div:nth-child(3){
    flex-grow: 4;
}